Abstract

The optical-limiting behavior and two-photon absorption properties of four novel organic compound solutions in tetrahydrofuran have been investigated. An ultrashort laser source with 0.5-ps pulse width and 602-nm wavelength was employed. The transmissivities of the various 1-cm-thick solution samples have been measured as a function of the beam intensity as well as of the solute concentration. The measured results can be fitted on the assumption that two-photon absorption is the only predominant mechanism causing the observed optical-limiting behavior. Based on the intensity-dependent transmissivity measurements, the molecular two-photon absorption coefficients for the four compounds are presented.

Transmissivity of compound I solution in THF with a concentration of 5.1 × 10−2 M/L versus the input laser beam intensity. The solid curve is given by Eq. (2) with a fitting parameter of β = 0.8 cm/GW.

Transmissivity of compound I solution in THF versus the solute concentration. The solid curve is given by Eq. (4) by using a fitting parameter of σ2 = 2.6 × 10−20 cm4/GW. The input intensity I0 = 2.21 GW/cm2.

Optical-limiting behavior of compound I solution in THF with a higher concentration (1.5 × 10−1 M/L). The solid curve is given by Eq. (4) by using the same fitting parameter of σ2 = 2.6 × 10−20 cm4/GW; the straight dashed line is given by assuming a linear medium with σ2 = 0.